DAMAGE DEACTIVATION

A phenomenological algorithm, motivated by the ''mode I'' microcrack opening and closing mechanism, is developed for the deactivation and reactivation of the damage effects as modeled by certain continuum damage mechanics theories. One-dimensional formulations with and without coupled plasticity are used to elucidate concepts associated with damage deactivation and to suggest multidimensional deactivation formulations applicable to continuum damage theories that employ a second-order tenser as the damage measure. Strain-based projection operators are used to deactivate the damage effects in the damage tenser. Motivated by observations from one-dimensional coupled formulations both the total and elastic strains must be compressive for damage to be rendered inactive. By introducing smooth functions to represent the avoided To illustrate the aspects associated with deactivation, a consistent set of examples using a strain-controlled one-cycle uniaxial stress loading is given for each formulation